Treatment of motor fuel



Patented Sept. 17, 1935 UNITED STATES TREATMENT OF MOTOR FUEL Wayne L.Benedict, Chicago, 111., assignor to Uni-. versal Oil Products Company,Chicago, 111., a

corporation of Delaware No Drawing. Application February 16, 1934,

Serial No. 711,555

16 Claims.

This invention relates more particularly to treatment of gasolinefractions produced in cracking the heavier and less valuable portions ofpetroleum and other similar materials though it is also applicable tothe treatment of corresponding straight run fractions.

In a more specific sense the invention is concerned with thepreservation of valuable properties of either raw or treated gasolinesunder the usual conditions of storage during which the gasolines areexposed to the influence of light and oxygen in varying degrees.

Cracked motor fuel fractions which have not been subjected to refiningtreatments stand generally in contrast to straight run gasolines inseveral respects. They frequently have a higher sulphur content whichaccounts principally for their unpleasantodor and they are subject torapid deterioration on standing due to polymerization and condensationreactions among the various types of olefins which constitute asubstantial percentage of the hydrocarbons which go to make up theirtotal composition. To ofiset some of these disadvantages the crackedproducts have a uniformly higher knock rating than straight runproducts, though this may also depreciate to some extent along with theloss of color and the development of gums which usually occur si-.multaneously though not necessarily so.

In rendering gasolines sufficiently stable to permit their storage overreasonable periods of time two general courses of action are open, thefirst consisting in treating out the oflending constituents by means ofchemicals and by polymerization reactions induced by condensing agentsand various solid contact materials and the second consisting in usingsmall quantities of antioxidants or inhibitors to stabilize the morereactive di' and tri olefins and render them less readily polymerizedunder the influence of oxygen. It is with processes of the lattercharacter involving the use of a particular class of compositeinhibiting materials that the present invention is concerned.

The deterioration of gasoline; particularly cracked gasolines, after acertain period of storage, is evidenced generally by the development ofa perceptible color or haze as a matter of direct observation and by anincrease in the gum or resin content and a loss in anti-knock propertiesas determined by evaporation tests and engine runs respectively. Thesechanges involve only a very small percentage of the total constitutentsof thegasoline and it is difiicult to follow their course without usinganalytical and test methods of an unusual degree of refinement. Thetypes of compounds responsible for the changes vary with the chargingstock originally cracked and the severity of the conditions of crackingso that the actual steps in the deterioration in respect to color,translucency', gum content and anti-knock value may takeplace indifferent order and in varying degree in dif-. ferent cases. In the caseof gasolines which have had light chemical treatments such as treatmentwith sulphuric acid, caustic soda, plumbite solutions, etc., the changesamong the minor quantities of unstable components may be furthercomplicated by the presence of chemical reaction products such assulphuric .acid esters, organic disulfides, etc., so that altogether thecourse of the different reactions leading to the deterioration'ofpropertiesmay have many diverse aspects.

To offset and retard the undesirable changes 20 in gasolines understorage conditions without severe chemical treatments entailing highlosses, the art of using very small amounts of the socalled inhibitorshas been developed to a considerable extent. While the inhibiting actionof power to retard to an unusual and unexpected extent the various typesof changes which take place in unstable gasolines under storageconditions.

In one specific embodiment the present invention ccmprisesthe use ofcompounds formed by the interaction of wood tar fractions and aliphaticamines to substantially retard the development of gums, color andcloudiness and the loss in anti-knock value commonly suffered by crackedgasolines under storage conditions.

We have determined as a result of experiments employing both inhibitorsfor preventing color and haze formation and those acting principally toprevent gum formation that unexpectedly good results are obtained whenusing a material which contains the reaction products formed betweenaliphatic amines and certain constituents of wood tars which are weaklyacidic in character. The exact nature of these compounds as theyoriginally occur in the wood tar is not well known and consequently thechemical nature of the compounds formed is also indefinite. Whendifferent aliphatic amines are added to wood tar there are indicationsthat chemical reactions take place as evidenced by a small but definiteevolution of heat, and the further observation that the inhibiting valueof the wood tar fraction in respect to preventing color and gumformation is better than before. It,is difficult and impractical toanalyze the products of these reactions and little value would be gainedthereby so that no attempt is made at this time to explain the observedphenomenon on a strictly chemical basis.

Y In respect to the wood tars employed as one reacting constituent tounite with aliphatic amines and form the present type of compositeinhibitor, it has been previously noted that the relatively heavy, oilyor tarry portions of the distillates of wood of different types,particularly hardwoods, are practically always utilizable as a source ofinhibiting materials for use in retarding the deterioration of gasolinesin storage, particularly in regard to gum formation and loss inanti-knock value, and it has also been determined in the case of anumber of woods, that particular boiling range fractions may be selectedwhich have superior value in this-respect.

The selection of a wood tar fraction for reaction with aliphatic aminesto form compounds useful in preventing the deterioration of any givengasoline on storage will be determined by consideration of a largenumber of factors. Primarily, the chemical composition of cracked andstraight-run gasolines from different sources will vary markedly inrespect to the percentages of those classes of compounds which requirestabilization by the use of inhibitors. For example, when crackedgasolines are produced under relatively high temperatures and lowsuperatmospheric pressures by' processes currently known as vapor phasecracking processes, the percentages of di and tri-olefins may berelatively high, resulting in a pronounced tendency towardpolymerization with attendant depreciation in value of the gasolinestock. In such cases, more highly efficient wood tar fractions may beused, since in general the observed gum inhibiting power of a fractionwhich has been reacted with aliphatic amines is of the same relativeorder as the original unreacted wood tar cut, although considerablyaccentuated, as will be later shown. When more nearly saturatedgasolines are produced from intermediate petroleum distillates of.

a relatively saturated character and under higher superatmosphericpressures and lower temperatures, either smaller amounts of the moreefilcient fractions or the same amounts'of relatively less eflicientfractions may be combined with the amines to form compounds which willefl'ect the and good fractions are frequently found boiling at pointsbetween 220 and 320 C. The use of higher boiling fractions is sometimeslimited by the fact that they impart color or cloudiness to gasolinestoan undesirable extent. According to the present invention, however,this color and haze efiect is materially lessened by the pretreatment ofthe wood tar fraction with aliphatic amines.

In regard to the compounds which are reacted with wood tar fractionsto.form inhibitors according to the present process it may be statedthat the broad class of aliphatic amines includes all compounds in whichthe hydrogen atoms of ammonia are partly or completely replaced by alkylresidues. The replacement of one ammonia hydrogen atom, as in thecompound ethyl amine, (CzH'sNHz), forms a series of compounds known asprimary amines; replacement of two hydrogen atoms, as in the compounddiethyl amine ((C2H5) 2NH) forms the series of secondary amines and thecomplete replacement of all three hydrogen atoms, as in the compoundtriethyl amine ((C2H5)3N), forms a series of compounds known as thetertiary amines which are also called nitrile bases to distinguish themfrom alkyl cyanides or acid nitriles.

The tertiary amines show their alkaline character by forming directaddition compounds with such acids as hydrochloric and picric acids, forexample, the hydrochloride of triamylamine has the formula N(C5H11)3.HCIand the picrate has the formula CsH2.(NO2)3.ON.H(C5H11)':{.

Any of the primary, secondary or tertiary aliphatic amines may beemployed in the present 35 connection when they show sufficientreactivity with the wood tar fraction to be employed and when thereaction produces an economical increase in the inhibitingeffectiveness. However, the alternate use of various members of theclass of aliphatic amines is not to be taken as evidence that theyfunction in an exactly equivalent manner.

The following list shows a number of representatives of the generalclass of aliphatic amines although it is not intended to be-complete butmerely indicative of the type of compounds which may be reacted withwood tar fractions to form composite inhibitors of variable inhibitingpower.

Trlmethylnmine Cyclohcxylzunimu.- 2 Aminom-octune Triethylamine...Di-n-butylnmine Trihutyla1nine 1 Diallylamine Dl-iso-butylmninmDi:uuylnmipe Tripropylamine .n-lieptylamine .TriamylaimueDicaprylamz'n'e I have determined that, when aliphatic amines of theabove character are reacted with wood tar fractions to form compoundswhose use in gasoline constitutes the subject matter of the presentinvention, both the color and the gum inhibiting properties of thecompounds thus produced are greater than the sum of those possessed bythe equivalent amount of aliphatic amine as a color inhibitor and of thewood tar fraction as a gum inhibitor respectively. The reason for thiscooperative action is obscure and probably involved in. some way in thechain of reactions which is supposed to occur during. the oxidation ofthe unsaturated hydrocarbons present in gasolines. Obviously a number ofalternative composite inhibitors exist due to the variable character ofdifferent wood tar fractions employed and to some extent the amount andcharacter of the amine reacted therewith, although the differentcomposites are not exactly equivalent in their inhibiting value.

As to the amount of material necessary to secure eflective inhibitingaction only general ranges can be given on account of the widevariations in stability of different gasolines but in general the weightof composite material on a basis of the gasoline stabilized will varyfrom, approximately 0.005 to 0.10%.

In regard to haze-forming tendencies in gasolines, it is frequentlynoted that this occurs in gasolines which contain relatively highpercentages of sulphur, particularly dissolved sulphur or organicdisulfides such as may be present as a result of plumbite sweetening.The use of the triamylamine-wood tar-compounds is found to beparticularly effective in preventing haze or cloud-formation in suchgasolines.

The following examples are introduced to show the general character ofthe improved results obtained when utilizing compound inhibitorscharacteristic of the presentinvention. While the data arerepresentative they only include four selected examples from a largenumber of cases, and obviously the scope of the invention is not to belimited to the specific figures shown.

Example 1 Triamylamine was reacted with a hardwood tar fraction boilingbetween the approximate range of from 240 to 280 C. Approximately 3parts of the wood tar fraction was mixed with one part of triamylamineat ordinary temperatures, agitation being used until the reaction wasevidently complete as shown by no further evolution of heat. Thecomposite inhibitor thus made was used in a commercial blended'gasolinefrom the mid-continent area consisting of 62.5% of cracked gasoline,20.5% ofstraight run gasoline and 17% of absorption gasoline. The datain the following table were obtained by adding small amounts ofcomposite inhibitor to the gasoline and noting the time elapsing beforea definite haze was observed when the raw and inhibited samples wereexposed to sunlight under standard conditions, the samples beingcontained in spe- I cially selected 8 ounce glass sample bottles.

Stability tests in the, glass bottles I Made by combining 3 parts byweight of wood tar traction with 1 part by weight of triamylamme. V

An examination 01' the above data will show that the use of an amount ofthe composite inhibitor containing given percentages either oftriamylamine and wood tar gave a longer time of freedom from haze thanwhen using the equivalent uncombined amounts of either triamylamine orwood tar alone. For instance in Example 1. in the second part of. thetable, even though the weight of reacted wood .tar in the compositeinhibitor was considerably less than the weight of unreacted fractionused alone in the check or blank test, the time before haze formationwas increased to a remarkable extent, to wit, from 35 to 240 minutes. Inpart I of the same table there is an increase of from to minutes whenthe given weight of triamylamine is used in combination with 3 times theweight of wood tar fraction, as compared with the use of triamylaminealone.

Example 2 In further substantiation of the value of using the precedingcomposite inibitor, the results obtained on another sample of blendedgasoline in which tests were made in quartz bottles exposed to the lightof a carbon are are in point.

It-is again evident that the composite inhibitor made by chemicallyreacting given proportions of triamylamine and wood tar fractions hasgreater inhibiting effectiveness than the same amountsof either reactingconstituent used separately.

Example. 3

Dicaprylamine was reacted with a hardwood tar fraction boiling betweenthe approximaterange of from 240 to 280 C. In this case approximately-2parts of the wood tar fraction was mixed with 1 part of dicaprylamine.at ordinary temperatures, agitation being used until the reaction wasevidently complete as shown by no further evolution of heat. Thecomposite inhibitor thus 7 .made was-fused in the same blended gasolineused in'Examples :1 and'2. The data in the following table were obtainedby adding small amounts of composite inhibitor to the gasoline andnoting the time elapsing before a. definite haze was observed when theraw and inhibited samples were exposed to an are light under standardconditions, the samples being contained in specially selected 4 oz.quartz bottles.

Haze stability tests in quartz bottles Percent dicaprylammo I, tCondition of sample in wood I 15 minutes 30minutes ifiminutes No 0.None. Haze. Very hazy. Cloudy. 1%085 1:110:10. glee! (30+). Clear (28).Very taint haze.

one 01 Ble- Composite0.005 e01 C1ear(20). Clear-{25). Clear (2;

.Ezampl 4 In further substantiation of the value of using the compositeinhibitor of Example 3, the results obtained on another sample ofblended gasoline in which tests were made in quartz bottles exposed tothe light of. a carbon arc are in point. The sample of gasoline employedin the tests consisted -of 45% straight run, 45% cracked and 10% naturalgasoline, all from the mid-continent producing area. The samples wereexamined at 2.5 minute intervals.

Percent Remained Haze Percent diceprylamine wood tar clear appearedfraction minutes minutes None. None. 2. 5 None. 0. 01 2. 6 0. None. 5 7.5 Composite 0. 001 0.01 7. 5 10 I 0. 0015 None. 7. 5 10 Composite 0.0015 0. 01 l l2. 6

0. 0021 None. 12. 15 Composite 0. 0021 0. 01 11. 5 20 0. 0025 None. 12.5 15 Composite 0. 0025 0. 01 22. 5 25 0. 003 None. 17. 5 20 Composite 0.,003 0. 01 35 37. 5

It is again evident that the composite inhibitors made by chemicallyreacting given proportions of dicaprylamine and wood tar fractions havegreater inhibiting effectiveness than the same amounts of eitherreacting constituent used separ'ately.

It will be observed by reference to Example 3 that the addition of 0.01%of wood tar fraction alone had no effect on the haze properties of theblended gasoline. However, when the dicaprylamine was reacted with thisportion of the wood tar, the sample remained clear for a longer periodof time than even the sample with the dicaprylamine alone since thelatter showed a faint haze at the end of 45 min. while the former wasstill clear though the color had dropped somewhat.

The character'and objects of the invention will be apparent to thoseskilled in the art to which it appertains from a consideration of theforegoing specification and numerical data included therein, althoughneither section is to be employed in a limiting sense upon the generallybroad scope of the invention.

I claim as my invention:

1. A process for the treatment of cracked hydrocarbon oil ofsubstantially gasoline boiling range to prevent deterioration thereof inrespect to gum and color formation and depreciation of anti-knock valuewhich comprises, adding thereto a relatively small amount of, thereaction product formed by the admixture of a wood tar and an alkylamine. V

2. A process for the treatment of cracked hydrocarbon oil ofsubstantially gasoline boiling range to prevent deterioration thereof inrespect to gum and color formation and'depreciation of anti-knock valuewhich comprises, adding thereto a relatively small amount of thereactionproduct formed by the admixture of a wood tar inhibitor andtriamylamine.

3. A process for the treatment of cracked hydrocarbon oil ofsubstantially gasoline" boiling range to prevent deterioration thereofin respect to gum and color formation and depreciation of anti-knockvalue which comprises, adding to the cracked hydrocarbon oil arelatively small '300" F., and a trialkyl amine.

amount of the reaction product formed by the admixture of a hard woodtar distillate boiling above 220 F., and below 300 F., and an alkylamine.

drocarbon oil of substantially gasoline boiling range to preventdeterioration thereof in respect to gum and color formation anddepreciation of anti-knock value which comprises, adding to the crackedhydrocarbon oil a relatively small amount of the reaction product formedby the admixture of a hard wood tar. distillate boiling above 220 F.,and below 300 F., and a trialkylamine.

5. A process for the treatment of cracked hydrocarbon oil ofsubstantially gasoline boiling range to prevent deterioration thereof inrespect to gum and color formation and depreciation of anti-knock ,valuewhich comprises, adding to the cracked hydrocarbon oil a relativelysmall amount of the reaction product formed by the admixture of a hardwood tar distillate boiling above 220? F., and below 300 F., andtriamylamine.

6. Motor fuel comprising cracked gasoline containing a -relatively smallamount of the reaction product formed by the admixture of a wood tarinhibitor and an alkyl amine.

7. Motor fuel comprising cracked gasoline containing a relatively smallamount of the reaction product formed by the admixtureof a wood tarinhibitor and triamylamine.

8. Motor fuel comprising cracked gasoline. containing a relatively smallamount of the reaction product formed by the admixture of a hard woodtar distillate boiling above 220 F., and below 300 F., and an alkylamine.

9. Motor fuel comprising cracked gasoline containing a relatively smallamount of the reaction product formed by the admixture of a hard woodtar distillate boiling above 220 F., and below 10. Motor fuel comprisingcracked gasolin cont ining a relatively small amount of the reactioproduct formed by the admixture of a hard wood tar distillate boilingabove 220.F., and below 300 F., and triamylamine.

11. A stabilizing agent comprising the reaction product formed by theadmixture of a wood tar inhibitor and an aliphatic amine. I

12. An inhibitor comprising the reaction product formed by the admixtureof triamylamine and. a hard wood tar distillate boiling between 220 F.and 300 F. i

13. The method of stabilizing gasoline normally tending to deteriorateby oxidation during storage which comprises incorporating into thegasoline a relatively small amount of the reaction product formed by theadmixture of a wood tar inhibitor and an aliphatic amine. 14. Motor fuelcomprising gasoline which tends to deteriorate by oxidationduring-storage and stabilized against such deterioration by theincorporation thereinto of a relatively small amount of the reactionproduct formed by' the admixture of a wood tar inhibitor and analiphatic amine.

15. The method of improving wood tar inhibitor which comprises adding analiphatic amine thzretu and reacting the same with components of thewoodtar inhibitor. F

16. The method of improving the inhibiting properties of hard wood tardi'stillate which cornprises adding triamylamine thereto and reactingthe same with components of the distillate. WAYNE L. BENEDICT.

4. A process for the treatment of cracked hy- .5

